Blower systems have been used in connection with heating, ventilating, air conditioning, and/or pressurizing systems for vehicles. Typically, such blower systems have one or more fans, squirrel cage blowers, or the like, which are turned at relatively high velocity to blow air into the vehicle operator's station or cab, for example, for ventilating and/or pressurizing purposes. Sometimes the air is blown proximate heating or cooling coils before entering the cab for heating or cooling the latter. Electric motors have been used to turn the fans, blowers and the like.
However, such electric motors have encountered a number of problems. With the increasing size of the vehicle cab, the capacity of the blower system, including the motor thereof, increases, thus resulting in a substantial electrical drain on the vehicle battery and/or electric power generating system as well as requiring an unnecessary increase in the size, weight and cost of such parts and support structure therefor and/or the output capacity of the vehicle engine. Moreover, such electric motors often require service or maintenance, including lubricating, cleaning, and the like, and, even so, frequently have a useful life expectancy, i.e. about 3,000 hours, that is shorter than the total vehicle life due to wear out of brushes, insulation, etc., thus requiring periodic replacement. Compounding these maintenance problems is the dirt which may enter the motor and cause excessive wear, for although the input air may be filtered, it is not uncommon for dirt to gain access to the motor, especially when the filters are dirty. The wearing out of the fixed supply lubrication to motor bearings, and commutator arcing further reduce the life expectancy of such motors.
One example of a prior blower system for a vehicle employs a DC electric motor having a double output shaft, one on each side of the motor, for turning two squirrel cage blowers simultaneously. The manufacturing tolerances for such a DC motor must be maintained relatively close for quiet, effective, and efficient operation. However, a certain amount of bending torque may be applied to the drive shafts by the weight of the respective blowers mounted and/or turned thereby, which may cause excessive wear on the various parts of the motor, including particularly the sealed bearings thereof. Alternatively, if the bearings are not sealed, they may reqire relatively frequent lubricating to avoid excessive wear.